Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 220435
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1135 PM CDT THU MAY 21 2015

.SYNOPSIS...
ISSUED AT 311 PM CDT THU MAY 21 2015

THE LATEST SFC ANALYSIS WAS INDICATING A TROF EMBEDDED IN CYCLONIC
FLOW DROPPING EAST-SOUTHEASTWARD ACRS THE UPPER MS RVR VALLEY INTO
THE WESTERN GRT LKS...WITH EVEN A SFC LOW REFLECTION LOCATED JUST
NORTH OF GRB WI. ALOFT...THE LATEST WATER VAPOR LOOP WAS INDICATING
A STRONG VORT PUSHING EAST OF THE AREA ACRS NORTHERN INDIANA WHILE A
SECONDARY VORT WING WAS NOTED ACRS FAR SOUTHERN MN INTO WESTERN WI.
OTHER VORT SPOKES WHERE ALSO SEEN EMBEDDED IN CYCLONIC FLOW ACRS
WESTERN ONTARIO CANADA.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 311 PM CDT THU MAY 21 2015

TONIGHT...THERMODYNAMIC MESO-ANALYSIS SUGGESTS A PLUME OF STEEP LLVL
LAPSE RATES DROPPING TOWARD THE AREA OUT OF MN/WI. A FEW HIRES NEAR
TERM MODELS COMBINE THE WAVE MENTIONED ABOVE JUST TO THE NORTH OF
THE AREA AND THIS STEEP LAPSE RATE PLUME TO DEVELOP A WING OF SCTRD
SHOWERS OR EVEN A THUNDERSTORM ARCHING SOUTHEASTWARD THRU THE DVN
CWA GENERALLY FROM 22Z TO 02Z OR SO THIS EVENING. ENHANCED BAND OF
CU SEEN ON CURRENT VIS SATELLITE LOOP IN THIS UPSTREAM AREA JUST TO
THE NORTHWEST OF THE CWA. BUT WILL BANK ON DRY AIRMASS IN PLACE
LOCALLY ESPECIALLY IN THE LOWER HALF OF THE COLUMN TO KEEP THIS AREA
JUST AN ENHANCED BAND OF CU AS IT DROPS SOUTHEASTWARD ACRS THE AREA
THIS EVENING AND WILL NOT MENTION ISOLATED SHOWERS/STORMS. WONDER IF
EVEN THE CU WOULD DECREASE SOME AS IT PROPAGATES DOWN ACRS THE CWA
OUT OF NORTHERN IA...BUT BAND OF DCAPE AND CU RULE PARAMETERS
CURRENTLY ASSOCIATED WITH THAT AREA OF FAR NORTHERN IA PROJECTED TO
SLIDE SOUTHEAST THIS EVENING AND WILL HELP SOME OF IT MAKE IT ACRS.
EVENING SHIFT WILL HAVE TO WATCH FOR ISOLATED TO WDLY SCTRD
CONVECTIVE DEVELOPMENT WITHIN THIS BAND...BUT AGAIN WILL NOT MENTION
IT FOR NOW IN THE FCST PACKAGE. WITH RATHER LOW DPTS EITHER IN PLACE
OR PROJECTED TO FLOW INTO THE AREA OUT OF MN...VEERING BUT
DECREASING SFC WIND PROFILES LATER TONIGHT...AND CLEAR SKIES AFTER
WHATEVER EVENING CLOUD BAND PUSHES THRU...WILL SIDE WITH THE COOLEST
OF LOW TEMP GUIDANCE OR EVEN UNDERCUT THOSE VALUES BY A DEGREE OR
TWO. EVEN THIS ACTION MAY NOT BE COOL ENOUGH ACRS THE NORTHWESTERN
THIRD OF THE CWA WHERE WOULD NOT BE SURPRISED IF SOME UPPER 30S
OCCUR IN NORMAL COOL AIR DRAINAGE LOCATIONS.

FRIDAY...WITH BOTH A RIDGE ALOFT AND LLVL HIGH PRESSURE SLIDING EAST
ACRS THE REGION...EXPECT A DRY MAINLY SUNNY DAY. DESPITE SOME
IMPROVING/MODERATING THERMAL PROFILES...WEAKER MIXING REGIME SHOULD
LIMIT FRI HIGHS TO THE UPPER 60S TO MID 70S ACRS MOST OF THE LOCAL
FCST AREA. SOME HIGH CLOUDS MAY SPILL IN FROM THE SOUTHWEST OFF
CENTRAL PLAINS ACTIVE SOUTHWESTERLIES AS THE AFTERNOON PROGRESSES...
BUT AGAIN SHOULD NOT RUIN SUNNY/MOSTLY SUNNY DAY WORDING.  ..12..

.LONG TERM...(FRIDAY NIGHT THROUGH NEXT THURSDAY)
ISSUED AT 311 PM CDT THU MAY 21 2015

DAILY THUNDERSTORMS CHANCES FROM SATURDAY NIGHT ON AND ASSOCIATED
ISSUES WITH COVERAGE/RAINFALL AMOUNTS/SEVERE THREAT ARE THE FOCUS OF
THE LONG TERM PERIOD.

FRIDAY NIGHT AND SATURDAY...

NO CHANGE TO PREVIOUS FORECAST IN KEEPING THESE PERIODS COMPLETELY
DRY. MODEL TRENDS CONTINUE TO SUPPORT MORE ROBUST UPPER RIDGING
ACROSS THE AREA WHICH SHOULD KEEP PRECIP AT BAY TO THE WEST.

SATURDAY NIGHT THROUGH MONDAY...

MODEL CONSENSUS NOW SUPPORTS HIGHER POPS WEST...LOWER EAST SATURDAY
NIGHT...WITH PORTIONS OF FAR NORTHWEST ILLINOIS POTENTIALLY DRY
THROUGH 12Z SUNDAY. THE MORE FAVORABLE MOISTURE RETURN WITH
DEWPOINTS IN THE 60S WILL HOLD OFF UNTIL THE DAY SUNDAY. RATHER
MEAGER INSTABILITY AND MARGINAL DEEP LAYER SHEAR SHOULD LIMIT THE
SEVERE THREAT...ALTHOUGH WITH PRECIPITABLE WATER VALUES AROUND 1.5
INCHES...POSSIBLY A BIT HIGHER...WE CAN EXPECT STORMS TO PRODUCE
SOME HEALTHY RAINFALL AMOUNTS. EASTERN IOWA IS FAVORED FOR THE
HIGHER AMOUNTS THROUGH SUNDAY NIGHT...PERHAPS IN THE 0.75 TO 1.25
INCH RANGE. CONFIDENCE IN LESS WITH THUNDERSTORM COVERAGE ON
MONDAY...ALTHOUGH WARMER TEMPERATURES OF 75 TO 80 WILL LIKELY
IMPROVE THE CHANCES OF A FEW STRONG TO MARGINALLY SEVERE STORMS.

TUESDAY THROUGH THURSDAY...

OPERATIONAL MODELS INDICATE A WIDE VARIETY OF SOLUTIONS AND POOR
CONFIDENCE IN GENERAL. THE CONSENSUS BLENDED POPS ARE IN THE 30 TO
50 PERCENT RANGE EVERY PERIOD...AS NO ONE PARTICULAR TIME FRAME CAN
BE RULED OUT. HOWEVER...THERE WILL BE SOME DRY PERIODS...ESPECIALLY
IF THE 21/12Z ECMWF TURNS OUT CLOSER TO REALITY. TEMPERATURES SHOULD
HOLD MAINLY IN THE 75 TO 80 DEGREE RANGE.    RP KINNEY

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1135 PM CDT THU MAY 21 2015

VERY QUIET VFR WEATHER WILL LAST THROUGH FRIDAY EVENING...WITH DRY
AIR AND CLEAR SKIES RESULTING IN WIDESPREAD VFR WEATHER IN THE
REGION. VISIBILITIES WILL BE UNLIMITED IN EASTERN IOWA AND
ILLINOISTHROUGH FRIDAY EVENING.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...12
SHORT TERM...12
LONG TERM...RP KINNEY
AVIATION...ERVIN



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